请教Prep PS1 162,180 解法（已找到讨论帖，请忽视该帖）

162.
    17030-!-item-!-187;#058&010961

If n and y are positive integers and 450y = n^3, which of the following must be an integer?

Ⅰ  y/3×2^2×5

Ⅱ  y/3^2×2×5

Ⅲ  y/3×2×5^2

(A) None

(B) I only

(C) II only

(D) III only

(E) I, II, and III

答案是B

List K consists of 12 consecutive integers.  If -4 is the least integer in list K, what is the range of the positive integers in list K ?

(A)  5

(B)  6

(C)  7

(D) 11

(E) 12

答案是B

不知道是怎么算出来的，请NN们帮忙给出解题思路。

谢谢！